1. New MPI (multiphoton ionization) and EI (electron impact) and published experimental data on and theories concerning the excited states of conjugated dienes were correlated. From this it was concluded that there is neither an experimental nor a theoretical basis for assigning valence excited states below the traditional lowest excited state. 2. The electronic spectrum of carbon disulfide was investigated by variable angle, variable incident energy electron impact spectroscopy. The results obtained were interpreted in conjunction with published data to yield a consistent assignment of the observed spectrum. 3. An improved photoelectron spectrum of the B state nitrous oxide ion was interpreted in terms of a novel set of vibrational interactions (Fermi Resonance). This interpretation should be generally applicable to many other linear triatomic molecules. 4. Correlations of Rydberg spectra of nine specifically methyl substituted dienes, measured by resonant multiphoton ionization spectroscopy, demonstrates that the predominant effect of methyl substitution is the alteration of the lowest ionization potential of the molecule.